The lake level seems to be down about a foot. Two rumours purport to account for this: either (a) the powers-that-be want us to get used to a new, lower level, so that we won’t notice when Dublin starts extracting water, or (b) the ESB is generating as much electricity as it can before it starts getting charged for water. Such charges would be covered by the same European Commission reasoned opinion as that mentioned here that might see Waterways Ireland being charged to fill the Grand, Royal and SEW.
Or, of course, it could just be that there hasn’t been much rain. According to Met Éireann’s seasonal summary for winter 2012 [two-page PDF]:
Majority of rainfall totals were below normal for winter across the southern half of the country and in some parts of the east. Rainfall totals were below average in the majority of these parts during December and January, while all stations reported dry conditions in February. Most stations the east and south reported a below average number of wetdays (days with 1 mm or more) and the driest winter since 2006 (6 years).
Ardnacrusha usually runs fewer turbines in summer.
Irish waterways history 